Epoxy flooring delaminates when the coating loses adhesion to the concrete substrate or separates between coating layers. Common causes include inadequate surface preparation, moisture transmission, contamination, weak concrete, incorrect primer selection and failure to follow the specified recoat window.
To prevent epoxy delamination, identify where the bond has failed and correct the underlying cause before applying a new coating system.
Epoxy delamination occurs when part of an epoxy flooring system separates from the material beneath it. This may appear as peeling, flaking, blistering or large sections of coating lifting from the floor.
There are three main types of failure:
Identifying the failure location helps determine whether the problem relates to the concrete, primer or coating system.
Poor surface preparation is a common cause of epoxy flooring failure. Concrete may contain laitance, curing compounds, dust, dirt or weak surface material that prevents the coating from bonding effectively.
Smooth or polished concrete may also lack the surface profile required for reliable adhesion.
To reduce the risk of failure:
Excessive moisture transmission can contribute to blistering, adhesion loss and delamination. Moisture problems may occur where concrete has not dried sufficiently, lacks an effective damp-proof membrane or is exposed to rising damp.
A concrete surface may appear dry while still containing moisture capable of affecting the coating system.
Before coating, investigate moisture conditions using appropriate testing methods. Where significant moisture transmission is present, a compatible moisture-control system may be necessary.
Fortis HydroFort VB Epoxy Vapour Barrier may be suitable for specified moisture-control applications, subject to substrate conditions and the current Technical Data Sheet.
A conventional epoxy primer should not be assumed to provide moisture vapour barrier performance.
Oil, grease, silicone, wax, cleaning chemicals and other contaminants can interfere with adhesion between epoxy and concrete or between successive coating layers.
Contamination may also be introduced through dirty application equipment, sanding materials or unsuitable cleaning procedures.
Before applying epoxy:
Surface contamination can also produce coating rejection and fish eyes. See Why Does Floor Coating Reject or Form Fish Eyes?
Epoxy primers improve adhesion and help control uneven absorption, but different concrete conditions require different primer characteristics.
Dense, porous, weak and moisture-affected substrates may need different preparation and priming systems.
| Concrete Condition | Recommended Fortis Option |
|---|---|
| Sound, properly prepared concrete suitable for self-priming | Fortis Coat 823 HS, where permitted by the system specification |
| Dry, porous concrete requiring rapid recoating | Fortis 823 Prime |
| Poor, porous or difficult concrete | Fortis 820 Prime |
| Concrete affected by significant moisture transmission | Fortis HydroFort VB, subject to moisture assessment and system suitability |
Fortis 820 Prime may be suitable for properly prepared, slightly damp concrete without standing water, subject to its current Technical Data Sheet. It is not a substitute for a moisture vapour barrier.
For a detailed comparison, see How to Choose an Epoxy Floor Primer.
Epoxy coatings cure through a chemical reaction. As curing progresses, the surface may become less receptive to subsequent coating layers.
Applying another coat outside the specified recoat window without suitable preparation can cause intercoat delamination.
To prevent this:
An epoxy coating cannot compensate for an unsound substrate. Weak concrete, dusting surfaces, poorly bonded repairs and deteriorating cementitious toppings may fail beneath an otherwise well-adhered coating.
If fragments of concrete remain attached to the underside of a detached coating, the failure may have occurred within the concrete rather than at the epoxy interface.
Remove unsound material, repair the substrate and verify its suitability before recoating. Adhesion testing may be appropriate where substrate strength is uncertain.
Two-component epoxy coatings require correct mixing ratios and suitable application conditions to cure properly.
Incorrect mixing, condensation, unsuitable temperatures, excessive film thickness or applying material beyond its working time may affect coating performance and adhesion.
Follow the manufacturer's mixing instructions, pot life, coverage rates, temperature limits and recoat requirements.
The appearance of a failed coating can provide useful clues, although visual inspection alone may not establish the cause.
| Observed Problem | Possible Cause | Recommended Investigation |
|---|---|---|
| Epoxy peeling from concrete | Insufficient preparation or contamination | Examine surface profile and adhesion |
| Concrete attached to detached epoxy | Weak concrete or substrate failure | Assess concrete strength and integrity |
| Bubbles or blisters beneath coating | Moisture, trapped gas or pressure-related defects | Investigate moisture conditions and blister contents |
| Topcoat separating from intact primer | Intercoat adhesion failure | Check recoat window and surface preparation |
| Localised peeling near oily areas | Surface contamination | Investigate contamination penetration |
| Widespread coating failure | Substrate, moisture or system-related problems | Conduct a broader failure assessment |
For related surface defects, see Why Do Bubbles and Pinholes Form in Epoxy Flooring?
Localised epoxy delamination can sometimes be repaired without replacing the entire flooring system. However, applying another coat over loose or poorly bonded epoxy will not correct the underlying problem.
The repaired area may remain visually distinguishable from the surrounding floor.
Where adhesion failure affects large areas, complete removal of the defective flooring system may be required.
Before installing a replacement system, assess concrete strength, moisture conditions, contamination and surface preparation requirements.
Successful epoxy flooring depends on treating the concrete substrate, primer and finish coats as a complete system.
Correct substrate preparation and system selection are more effective than attempting to compensate for poor adhesion with additional coating thickness.
Fortis Adhesives & Coatings manufactures epoxy flooring products in Melbourne, Australia, for industrial, commercial and residential applications.
Explore the complete Fortis Epoxy Floor Coatings range for additional flooring systems and technical information.
Epoxy can peel when adhesion between the coating and concrete is insufficient. Common causes include inadequate preparation, contamination, moisture transmission, weak concrete or unsuitable primer selection.
Yes. Moisture transmission and associated pressure or chemical processes can contribute to blistering and adhesion failure. Investigate the moisture source before recoating.
Yes, provided the existing coating is compatible, sound, firmly bonded and correctly prepared. Cleaning and mechanical abrasion may be required, particularly where the original recoat window has passed.
No. Some epoxy flooring systems can self-prime properly prepared concrete. Separate primers may be necessary for porous, difficult or moisture-affected substrates, depending on the system specification.
No. Loose or poorly bonded coating must be removed and the underlying cause corrected before a compatible replacement system is applied.
New concrete commonly requires approximately 28 days of curing before conventional epoxy application, but age alone does not establish suitability. Moisture condition, concrete strength and the coating manufacturer's requirements must also be satisfied.
Correct concrete preparation, moisture assessment, contamination removal, compatible primer selection and adherence to specified application and recoat conditions are the most important preventative measures.
Choosing the correct epoxy flooring system starts with understanding the concrete substrate, moisture conditions, surface preparation requirements and intended service environment.
Fortis Adhesives & Coatings manufactures epoxy primers and floor coatings in Australia and can assist with product selection and system compatibility.
For technical advice on epoxy delamination, substrate preparation or selecting a suitable coating system, contact the Fortis technical team.
Technical note: This guide provides general troubleshooting information. Delamination causes may require on-site investigation, adhesion testing and moisture assessment. Always refer to current product Technical Data Sheets and project specifications before application.